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MG MGB Technical - Pulling engine and trans

I will be pulling the engine and trans from my 79 B and I am asking for any tips or tricks others have developed or used in the past to make it easier for one man to accomplish. I do have the mechanical equipment to support the components but I am finding it difficult to find a "manual" of steps or procedures to help make it smooth. Any help is appreciated!!
Peter Murray

Peter-
Before you begin, you will need to have a proper Service Manual. I would recommend that you purchase a reprint of the original factory service manual that the MG dealers had for their mechanics to consult. To my knowledge, there is nothing that can compare with it for completeness. Its actual title is “The Complete Official MGB,” although it is often called “The Bentley Manual” as it is printed by Bentley Publishers. Their website can be found at http://www.bentleypublisher.com/ where you can order it direct.
Pulling the engine and transmission out of the car need not be an exercise in fear. Get at least one friend to help out, as it is not an easy job on your own. Although it may seem that the removal would be easier if the engine and transmission were separated while still in the car, the easiest way is to pull the engine and transmission as one unit with your engine hoist located directly in front of the car. It is possible to pull the engine separately, but to do so incurs the risk of damaging the first motion shaft of the transmission. In addition, realigning the engine with the transmission still in place can be maddening.
First, disconnect the ground (earth) on the battery. You may find that it is best to remove the crankshaft’s harmonic balancer pulley wheel retaining bolt prior to removing the engine from the car. The crankshaft’s harmonic balancer pulley wheel retaining bolt in the end of the crankshaft is not standard Whitworth, but is of Whitworth form: Diameter 1 5/8", 16 TPI, 1 1/16 full thread. If it is found necessary to clean up the thread, the operation must be confined to cleaning up only. This thread is highly stressed and must always be up to full size. Thus, it is not correct to use an American - SAE - UNF form tap in order to clean these up, though you might get by in the end of the crankshaft, but definitely not on the bolt. To my knowledge, this is the one and only British form threaded fastener on any of these engines. Note that BSF is 5/8-14, and not 16 TPI. UNF is 5/8”-18. CEI starts with 20 TPI at ½" and up. In order to remove the crankshaft’s harmonic balancer pulley wheel retaining bolt, the most professional method is to use an impact wrench. This method has the advantage that you do not have to worry about blocking the flywheel (if engine is separated from transmission, or blocking the wheels with transmission in gear). Another, and much more common, method for loosening the crankshaft’s harmonic balancer pulley wheel retaining bolt is to place your 1 5/16” wrench / breaker bar against the left chassis rail (as you are sitting in the car). Put some wood or something soft against the chassis rail in order to prevent scratches. Disconnect the coil so that the engine cannot start. Blip the starter briefly, and the bolt will be jarred loose.
Remove the gearshift lever (gear change lever) surround, raise the gearlever boot, then unscrew the gearshift lever (gear change lever) retaining bolts and lift out the gearshift lever (gear change lever). Drain the oil from the sump and disconnect the oil cooler hoses (flexible pipes) from both the engine block and the oil filter stand, and then disconnect the oil pressure gauge hose (flexible pipe) from the engine. Disconnect both the throttle and choke (mixture control) cables, then disconnect the fuel lines from the carburettors. Remove the carburettors and intake manifold as a single unit, along with the exhaust manifold, fan, distributor, alternator, heater valve, hot water pipe, hot water hoses (flexible pipes) and oil filter stand in order to lessen the total amount of weight to be moved about and to protect these components from being damaged. If your engine is equipped with antipollution equipment, it should also be removed prior to attempting to remove the engine from the car. Drain the coolant from the radiator and, if you are fortunate enough to have a petcock installed onto the side of your engine, drain the engine block as well. Next, disconnect the thermal transmitter for the coolant temperature gauge, and then disconnect the coolant hoses (flexible pipes) from the water pump and the water outlet elbow. Now, crawl under the car. Do not forget to both disconnect the front mounting bracket for the exhaust system located on the bell housing of the transmission and remove the grounding strap. Chrome Bumper models had the ground strap on one of the front motor mounts where it connected the engine front plate to the chassis. The Rubber Bumper cars had their grounding strap on the right transmission mount where it connects from the forward bolt holding the transmission mount to the transmission and the transmission crossmember. While you are under the car, remove both the electric starter and its solenoid, the clutch slave cylinder from the bellhousing, as well as the speedometer drive cable from the main gearbox casing. Next, disconnect the driveshaft (propeller shaft) as well, and then disconnect the solenoid on the overdrive. Crawl out from under the car and then loosen the 3/8”-18 UNC bolts of the front motor mounts, then remove the gearshift knob and the shift boot retainer plate. Be aware that ¼ x 28 (fine thread) x ½” PoziDriv round head machine screws are used to attach the transmission tunnel cover to the transmission tunnel. The original screws are not Phillips head screws, although commonly mistaken for such. Be warned that if you use a Phillips head screwdriver, you will chew the heads up. If this mistake has already been made, replacements can be found at these firms: McMaster-Carr at: http://www.mcmaster.com/ , MSC at: http://www.mscdirect.com/ , or Metric Multistandard Components Corp at: http://www.metricmcc.com . Remind yourself of how much fun you are having, then crawl back under the car, and remove the bolts that secure the rear transmission mount to the underside of the car. Now, crawl back out from under the car and whistle a happy tune as you proceed to remove the 4 bolts that secure the oil cooler, and then remove the bolts that secure the radiator diaphragm. Remove both the radiator and the radiator diaphragm, along with the oil cooler and its hoses (flexible pipes) in order to give more room in which to maneuver the engine/transmission package and decrease the angle to which the engine/transmission package must be tilted, making removal much easier. This will also avoid damaging the radiator. Raising the rear axle of the car up about 8 to 12 inches on jackstands will allow the tail end of the transmission to drop down lower and give you a better relative angle. Beg, borrow, or buy an Oberg Tilt Lift load leveler mechanism so that you can alter the angle of the engine in order to allow maximum maneuverability as you lift it in cramped quarters and make the extraction much, much easier. You might feel that it is an unnecessary luxury, but it is worth every cent not to scratch up your paint or dent and/or crease the sheetmetal inside the engine compartment. This is why professional shops always have a load leveler for removing engines!
Removing the fan from the engine is a good idea if you are using a mobile engine hoist, as on some types of engine hoist it can catch on the engine hoist and be damaged. Place the base of the mobile engine hoist as close as possible to the engine bay and do not extend the arm of the mobile engine hoist any further than is necessary. Use the rocker arm studs as lift points only if you are certain that they are Original Equipment items as some of the replacement studs nowadays are of dubious quality. Most failures will occur as a load is applied at an angle to an attachment point, so make those attachments strong, or, better yet, make them nonexistent by using a sling. Although some use a length of chain enclosed in a bicycle inner tube, I prefer to lift the engine with a strap of heavy nylon webbing. Not only is it strong and easy to undo knots from, but its greater surface area in contact with the block makes slippage less likely to occur and it is less likely to damage paint. Pass the strap between the engine and its backplate, cross it over above the rocker cover and loop it under the water pump, and then tie the ends off with a simple square knot above the engine. With the hook placed behind the knot, it will not slip backwards, plus the square knot is self-tightening and will not slip either. Always remember the cardinal rule to never, ever, put any part of your body anywhere below a suspended motor.
When you prepare to reinstall the engine, leave it tilted with the gearbox at a lower level in order to make it easier for your fingers to install the bolts of the front mounts. Do not make the classic Beginner’s Mistake of tightening down the front motor mounts and then trying to install the rear crossmember mount onto the end of the transmission package. Instead, before attempting to install the engine, attach the rear crossmember mount onto the transmission and leave its mounting bolts loose. It is much easier to get the transmission bolts started by hand, and then tighten the front motor mounts with the motor hanging on the hoist before tightening the rear transmission mount. Tighten the rear transmission mount bolts using a half-height swiveling socket, with a four or five-inch extension. With this tool, you can get to those rear bolts a lot easier.
When new front motor mounts and their brackets are installed, inspection usually reveals that the assembly is already bending toward the block. That means it is prestressed in compression, and as the engine rocks the stress cycles from compression to tension and back again, ultimately leading to fatigue failure. This condition is at its most severe on the Left Hand bracket, since that side of the engine lifts under acceleration, whereas the Right Hand bracket tends to remain in compression, except during hard engine braking. If you fit a spacer of approximately 1/8” (.125”) thickness between the bracket and the block at the large bolt, you will prestress the bracket in such a way as to prevent the cycling through zero, which reduces or eliminates fatigue failure. This compressive preload also keeps the rubber mount plates parallel, greatly increasing the life of the mount itself. If the mounts are correctly shimmed then the force on the rubber mounts will be at right angles and they should not sag, even over a long period of time. The need for these shims is determined by the dimension across the mountings in the chassis, which varies due to build tolerances. You can determine if they are needed by examining the mounting rubbers - the sides should be at 90º to the ends when under the weight of the engine. If they slope towards the engine at the top, then you need to add shims. If they slope away from the engine, then you need to remove shims.
In the case of the motor mounts used in Rubber Bumper cars, the round type of engine mount (also used on the V8) theoretically does not need shims to correct the alignment as the chassis rail brackets have slots in them so that the studs can take up whatever position it needs to, that and the angled faces of both parts taking up any dimensional differences between the chassis rails likely to be encountered. However, the stud on the mounting rubber will not drop lower than the point where the steel disc hits the ledge at the bottom of the chassis rail. Consequently, most Rubber Bumper MGBs have two spacers on each side. When the motor is raised, you can carefully hold the nut and spin the mount to get it together. Under the bolt head you will need to fit a thick washer that has been contoured to fit inside the bracket. If this bolt is bottomed in the hole the bracket will break, and the threads will be damaged when you remove it. These extra spacers will require a slightly longer bolt. The use of Loctite will ensure that the large bolt does not work loose. If it does, it will cause the bracket to fracture across its bolt hole, in addition to the usual crack at the bend. Do not omit the shim plates, and be sure the mounts are driven to the bottom of the slots in the frame (if the original square offset spacers are fitted, they will only fit with the mount all the way down at the bottom). Note that the square spacer has an offset hole. The mount stud goes all the way at the bottom of the slot in the frame (tap it down with some weight on the mount), and the offset of the square spacer serves to keep it there so it cannot move upward should it became loose. Because the threads are usually damaged, run a die over the threads before installation so that the nut will be free-running. Use anti-seize compound on the threads. Install the square spacer under the bracket so that its widest part is uppermost, it just fits up against the top edge of the cavity. It helps if you can get the underside of the frame bracket clean and use adhesive to hold the square washer up while you install the nut and lockwasher.
Determining if you need to shim the motor mounts is a simple matter because the rubber blocks deform if the engine is too low - the top and bottom faces will not be at right angles to the plate. Simply add shims equally to both sides until both of the rubber blocks sit square. If there are clearance problems with the bellhousing or the exhaust manifold/steering column, simply changing a shim from one side to the other will move the engine in the opposite lateral direction while leaving the engine at nominally the same height.
At first appearances, installation of the rubber bushings into the transmission mount seems a formidable task to many. The smaller of the bushing’s two flanges is 1 ¼” in diameter and about ¼” thick, while the hole through which it must pass is only about ¾” in diameter. It appears to be a job that requires a man with at least three hands. However, installation of the rubber bushings into the transmission mount is not as difficult as it seems. The hole through which it must pass is only about ¾” in diameter. First, a lubricant will make the procedure easier and protect the rubber from chafing. Secure the yoke in a vise. Tie off one end of a thin cord, in the direction of one end of the yoke. Loop the cord and pull it up through the yoke hole. Pass the loop around the bushing, and then place the edge of the bushing flange into the yoke hole. As you do this, it helps to use your free hand in order to oblongate the bushing. Initially, pull the cords almost parallel to the bushing groove. As more of the flange begins to enter the hole, change your direction of pull downward, until eventually you are pulling straight down. In this manner, you will gradually peel the circumference of the flange through the hole. Tying off the cord leaves one hand free to manipulate the bushing, and also to change the pull angle of the cords. Obviously, the wiser you are at choosing your tie-down point, the better this procedure will work.
Steve S.

there was a post all about this on the 5th of jan 2008 have a read of it. the only things i would advise is make yourself a lifting bar.to sling the engine.and if you are not working on the box then do not remove it. AT.
andy tilney

Thank you for that volume to digest prior to doing anything else. I am removing both compounts to replace the transmission and while there the rear engine seal and clutch assembly. I own the Bentley Manual however I have not seen anything like the tome written above in that book!
Peter

Have to somewhat disagree with Steve's first line.
If you have a good set of jackstands to lift the car to get the driveshaft unhooked and take out the transmission crossmember, and a engine hoist with one of the adjustable units to change the angle of the engine, removing and replacing can easily be done by a single person. Have done it at least three times.
Bruce-C

peter. as you asked for any tips on this job a few  spring to mind with regard to your back main seal replacement. When you get your new seal don't touch the lip, put it in soak in some clean engine oil until you are ready to use it, and try to get hold of a protector sleeve so you don't damage it as you refit the back bearer plate. If you can't get one I have seen people use some tape on the back of the crank smeared with oil, but remember, if you damage the seal it's engine out again, and my second tip is as you are doing this on your own, buy a 3/4A.F. impact socket(one with 6 sides) and machine off the lead at the start of the socket, so now the flats of the socket are flush with the bottom of the socket this will stop it slipping off as you are trying to hold the engine, lock the crank, and torque up the bolts all at the same time, which is easy done with those shallow headed bolts, if you look at the picture you will see what I am on about. AT

andy tilney

Peter-
If you are going to replace the rear seal on the crankshaft, I have a few suggestions:
While you have the engine out, you might want to consider replacing the front seal as well. The MGB front crankshaft seal (Moss Part # 120-000) tends to leak engine oil because there is not a built-in device for ensuring that the seal is properly centered with the crankshaft centerline after the seal is replaced. A special factory service tool that is slipped onto the crankshaft and into the seal after the timing cover is installed but before the timing cover bolts are tightened is supposed to accomplish this; I have never seen the tool offered for sale in the United States. However, there is an effective substitute: the crankshaft sprocket for the MGB simplex (single row) camshaft drive chain (BMC Part # 12H 4201, Moss Part # 460-425). When its tapered end is slipped onto the crankshaft and into the seal, it will center the seal perfectly while the timing cover is being torqued to its specified settings of 6 Ft-lbs for the ¼” bolts and 14 Ft-lbs for the 5/16” bolts. Be sure to not lose the elliptical washers peculiar to the timing cover (BMC Part #’s 2K 5197 & 2K 7440). These are necessary for spreading the sealing load evenly across the face of the flange of the timing cover. Keep them paired with their respective timing cover bolts as they have become very hard to obtain.
As an alternative for sealing the rear end of the crankshaft, an uprated single-lip crankshaft rear seal that was used in the version of the B series engine found in the Sherpa van will do an excellent job of keeping oil inside the engine over the long term (Rover Part # LUF 10002). Contrary to rumor, this oil seal is not a double-lipped design. A double-lipped seal is essentially a single lipped inner seal shrouded from dirt by an outer second lip. This usually extends the life of the seal and any extra sealing action is purely a bonus. The original seal worked just fine before the advent of sealed crankcases, but the vacuum present in the engine tends to draw stuff in. Most "double lipped" seals have the outer lip reversed in order to prevent ingress of dirt or air that can damage the seal and thus interfere with the maintenance of the vacuum inside of the crankcase. On the other hand, a true double-lipped seal would have both lips in the same direction, for good sealing against fluid escape. The seal dimensions are: Outer Diameter 4.125”, Inner Diameter 3.500”, Width .375”. Being made of Viton, they are not prone to failure until thermal conditions rise above 450° Fahrenheit. This can be obtained from Brit Tek (Brit Tek Part # AHU2242). When you examine the oil seal, notice that one side of the seal has a sharp edged lip while the other side does not. The side with the sharp lip also has a spring around the rubber. The spring holds the rubber in contact with the shaft and the sharp edged lip runs on the shaft. The sharp lip is what seals the oil. On the spring side you can see that oil under pressure would tend to assist the spring in keeping the rubber in contact with the shaft. Likewise, if installed backwards, oil pressure on the side opposite the spring would tend to lift the rubber and would oppose the spring, defeating its purpose. Simply pry the old seal out with a screwdriver. Its installation is quite straightforward. Make sure that the engine backplate is held in place with the bolts only finger-tight so that it can be moved by gently tapping it with a soft hammer. This may be necessary in order to properly center the new oil seal. Clean up the rear of the crankshaft as well as the hole in the engine backplate. Oil the crankshaft journal, and then slide the plastic adapter over the end of the crankshaft, with its big end first. Oil the outside of both the adapter and that of the seal, and then slide the seal over the adapter until it meets up with the backplate. Do not tap the seal directly with a hammer when installing it onto the engine backplate. Grease the outer rim of the seal and gently tap the adapter all around its circumference with a small hammer in order to drive the seal into place. Gently tap the seal until it is flush with the engine backplate and then pull off the adapter. Before torquing the 3/8”-24 UNF bolts of the engine backplate, give the backplate a gentle rotational wriggle to make certain that the seal is absolutely centered onto the crankshaft and is not pre-loaded by means of the engine backplate being slightly offset. Install the crescent-shaped locking plate (BMC Part # 1H 1021) with its four 5/16”-24 UNF bolts, and then bend the tabs up in order to retain the bolt heads in position.
Steve S.

Steve, I have just read your post on fitting a new back main seal,infact i have just read it 3 times,you talk about adapters to fit the seal in the back bearer plate which adapters do you mean are you talking about 18g 134 cq. AT ps for centering the timing cover seal why not use the crank pulley.
andy tilney

Andy-
Reread my previous posting. I use the simplex sprocket to center the seal for the front end of the crankshaft. For installing the rear seal I use the cheap plastic tool that comes with the rear seal. Both techniques have always worked for me, so I've never bothered to experiment with any other method.
Steve S.

steve thanks for your reply. it is very good when you get a seal protector in with the new seal, i have had these with other back main seals mainly fords but never with a B series back main seal, and never with an adapter to fit the new seal in with the seal aswell, i think i will try out one of these seals as we can't buy these here in the UK do you have a part number and an adress where i can buy some of these kits with a seal, seal protecter,and seal fitting adapter,all in the same kit, PS I have reread your previous post i was also talking about the seal for the front end of the crankshaft, as every one fitting a new timing cover seal will have a crank pulley to center the cover i don't think every one will have spare simplex sprocket to use,one other point i would like to ask, if you slacken all the bolts on the back bearer plate so you can move it what about the gaskets,also sticking a screwdriver in between, the seal and the crank to lever out the seal is not the best method i have seen a few cranks where this has been done to remove the seal and they have had the seal face damaged, far better to fit these seals by the approved method. AT
andy tilney

Andy-
I don't know of a source in the UK for the Sherpa seal, so Click on this: http://www.brittek.com/ (Brit Tek Part # AHU2242).
If the front seal is leaking, then the timing cover gasket can't be far behind, so I replace them both at the same time. As for the rear, the same is true. While the backplate is off, I remove the seal. Obviously, I hate leaks, and I can't stand doing anything halfway. Getting it right the first time beats pulling everything apart a second time.
Steve S.

This thread was discussed between 26/01/2008 and 27/01/2008

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